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Using Engineered Surfaces to Optimize Condensation in Refrigeration Systems

Cheshmak, Alireza | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57959 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Mousavi, Ali; Nouri Borujerdi, Ali
  7. Abstract:
  8. Undesirable water condensation is ubiquitous in highly humid environments. As the condensation of water is an exothermal process, it can lead to the energy efficiency reduction of heat exchangers utilized in heating, ventilation, and air conditioning (HVAC) systems installed in humid environments. Moreover, the wet surface introduced due to condensation can provide suitable conditions for bacterial proliferation and corrosion propagation. By considering these factors, providing durable yet affordable anti-condensation coatings seems crucial for heat exchangers in humid environments. In the present study, we aim to reduce water condensation by controlling water nucleation and growth stages on the surface through a cost-effective and versatile coating. In this regard, three different superhydrophobic coatings utilizing various combinations of silica and carbon black nanoparticles within the polyurethane resin matrix are manufactured to achieve anti-condensation coating with dropwise condensation mode. The fabricated coatings can potentially eliminate nucleation sites and postpone droplet formation time. The surface possessing two nanoparticles with a contact angle of 159.2° and contact angle hysteresis of less than 5° could establish a delay time of 18.8 min in droplet growth time and a 38% reduction in condensed water amount at a subcooled temperature of 5 ℃ with respect to bare aluminum. Moreover, this surface revealed good durability against abrasion test for 10 m, immersion in ammonia and ethanol solutions for 20 days, and subjection to a humid environment for 100 h, as the tested surface retains its superhydrophobicity after all these tests. In comparison to the literature, this study presents a comprehensive investigation of the anti-condensation ability of surfaces, which has rarely been investigated in other studies. Moreover, The durability of the fabricated sample is outstanding in comparison to what has been studied in the literature, which allows the fabricated surfaces to be used in various fields, utilizing cooled heat exchangers within a highly humid environment
  9. Keywords:
  10. Surface Wettability ; Dropwise Condensation ; Hydrophobic Materical ; Nanoparticles ; Nucleation ; Anticorrosive Coating ; Superhydrophilic Surface ; Anti Condensation Surfaces

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